Cartridges filled with liquid ink are used in a number of applications from an ordinary ball point pen to the more recently developed ink cartridge for thermal ink jet printers. Ink cartridges are typically made from plastic or some other relatively inexpensive material. The ink cartridge includes a chamber sufficiently large for holding an adequate supply of ink to enable a user to write or print a significant amount of text before the cartridge must be disposed of or refilled due to lack of ink. Many cartridges used in thermal ink jet printers have chambers filled with a medium which absorbs and holds the ink and supplies sufficient backpressure to prevent unintended leakage or "weeping" of liquid ink out of the nozzles onto a surface being printed.
A typical end-user product for thermal ink jet printers is a cartridge in the form of a prepackaged, frequently disposable item comprising a sealed container holding a supply of liquid ink or toner and, operatively attached to a printhead having a linear or matrix array of channels connected to ink ejecting nozzles. Generally the cartridge may include terminals to interface with the electronic control of the printer; electronic parts in the cartridge itself are associated with the ink channels in the printhead, such as the resistors and any electronic temperature sensors, as well as digital means for converting incoming signals for imagewise operation of the heaters. In one common design of printer, the cartridge is held with the printhead against a sheet of paper on which an image is to be printed, and is then moved across the sheet periodically, in swaths, to form the image, much like a typewriter. Full-width linear arrays, in which the sheet is moved past a linear array of channels which extends across the full width of the sheet, are also known.
Typically, cartridges are purchased as needed by the consumer and used either until the supply of ink is exhausted, or, equally, if not more importantly, until the amount of ink in the cartridge becomes insufficient to maintain the back pressure of ink to the printhead within the useful range. Many different types of ink saturating or wicking mediums are used in the chambers of ink cartridges and include foam rubber, foam plastic, felt, reticulated polyurethane foam, and thermoset melamine condensate
Of course, these cartridges need to be filled with a predetermined amount of ink, once, if the cartridge is disposable, or many times if the cartridge is refillable. In addition, because of the high demand for ink cartridges, an automatic filling apparatus is desirable to increase the manufacturing rate of the cartridges so that the customer requirements may be appropriately satisfied.
In U.S. Pat. No. 3,800,496 to Bardet, a machine for testing, filling, and sealing receptacles such as fountain pen cartridges is described. A cartridge is filled with a needle which receives an ink dose required for filling the cartridge, the ink dose is driven by a piston from a cylinder holding the dose.
U.S. Pat. No. 4,464,668 to Komai et al. describes an ink supply system for an ink jet recording apparatus which includes a supply pump for feeding ink to an accumulator for equalizing the pressure of the ink, and valve means for controlling the feeding of the ink under pressure to the recording head.
U.S. Pat. No. 4,633,923 to Hinzmann describes an apparatus for filling ink cartridges used in printer units of a cigarette machine, The apparatus includes a frame to support an empty cartridge for filling, a housing defining a chamber for holding ink, and a valving element for evacuating ink from the chamber to the ink cartridge.
U.S. Pat. No. 4,669,054 to Scrudato et al. describes a means for storing and introducing a metered supply of ink, to an ink cartridge during the operation of a printing device. Included is a bag container for holding ink, a conduit means for conducting ink to the ink cartridge, and a needle for penetrating an ink absorbing material contained in the cartridge.
U.S. Pat. No. 4,968,998 to Allen describes the resupply of liquid toner or ink to a print cartridge which is refillable at a service station in a printer. Liquid toner is forced under positive pressure to a refill tube on the print cartridge. Air and liquid toner are simultaneously evacuated from the cartridge through negative pressure through an evacuation tube on the print cartridge.